These kinds of projects really highlight how awesome embedded linux really is. It's the marriage of everything small embedded systems can do (gpio, analog inputs, low level communication protocols, ability to run on batteries, etc) with PC level specs, and the breadth of software that linux provides (every networking protocol under the sun, audio/video processing, countless languages to program with, etc). Best of all, the only thing you have to buy is the board, of which there are several offerings at $50 or less.
> Raspberry Pi 2 booting in 2.9 seconds
Has the kernel they mention been released anywhere?
I would start with rpi-buildroot and build up from there. If you have low latency audio questions feel free to email me.